View Full Version : Brake pad depth/thickness?
I may be asking a stupid question here... How thick are new pads generally?
I'm trying to establish whether mine need doing. I've read if there is less than 3mm then they need to be replaced. Mine are probably about this but that groove you get is still visible.
I am getting new Tyres fitted tomorrow and I'm tempted just to get the pads changed at the same time but don't want to prematurely.
I'm rubbish :(
I wouldn't change yet, think they only come with 5 - 6mm. Should be good down to 1 mm
Do they degrade with age? They are probably 5 years old now, 3 of which were sat doing nothing.
I have a strange braking problem too that I was hoping new pads may get rid of, they look a bit crumbly around the edges?
I don't know what is and isn't normal which is half the problem.
Just been doing some more Reading and I thinking the crumbling of the pads and judder at low speeds after very hard braking may be due to glazed pads?
Thinking back the problem only started after a trackday at rockingham so I may have over heated the standard non sintered pads?
Somebody correct me if I am wrong but is the groove not the wear indicator? If you can still see the groove the pads are still within the legal limit. Groove being there so you can easily see without having to take the calipers off and measure?
There is a very magrinal groove, my problem is I dont know how long that groove started, there is probably 1mm of groove left.
I'll be doing around 800 miles in wales in 2 weeks and dont want them running out or ruining the trip. But I'm not experience enough in dealing with/changing brakes to really know what to expect from them.
I guess the answer may well be to ask the mechanic doing the tyres but I lack trust in getting an honest asnwer from someone who is trying to make money out of me :(
My braking issue bothers me too...
When I brake hard from high speed the brakes feel great and stops me fine... but when I release the lever gently after braking at maybe 10mph or less I get a substantial judder/knocking, only sometimes through the front of the bike, not the lever.
It seriously bugger your confidence in the front brakes and part of it make me wonder if its what caused me to come off at Mallory when braking in a straight line.
Could this be glazed pads like searches on google are suggesting, it would explain the juddering and crumbling of the pads? so worth just changing the pads anyway.
They are standard organic pads by the way, so more likely to glaze with hard track use?
Red Herring
09-04-10, 04:17 PM
Given the relative low cost of pads and the planned journey I'd change the pads just for peace of mind. There's still some life in them so don't bin them, keep them as spares. Whilst at it check the discs haven't warped by spinning the front wheel and seeing if they "wander" and that the calipers and pistons move freely.
-Ralph-
09-04-10, 04:22 PM
I have about 3mm of pads and about 2mm of groove. They are the OEM pads and I've done 22,000 miles. I thought they were low when I had the bike apart comparing them to car pads, and I ordered new pads. When they arrived and they only had 5mm on brand new, I realised mine were only half worn and left them on the bike, the new pads are now in a a drawer in the garage waiting until I've done another 22k!
If you can still see a mm of wear indicator, your not going to need new ones because of a trip to Wales.
G am i right in thinking you own a CBR600RR?
Have you got standard pads or aftermarket pads?
Sorry if you have said but i missed it :)
G am i right in thinking you own a CBR600RR?
Have you got standard pads or aftermarket pads?
Sorry if you have said but i missed it :)
They are standard OEM pads, I think that makes them organic rather than sintered?
I have just been told I am mental for considering changing either Tyres or brakes just to put another spanner in the works.
I am thinking sod it right now I'll cope with occasional randomness from the brakes and slightly less grippy Tyres for Wales lol.
In that case the pads should have a wear marker about them selves some where, im not quite sure where but it should be pretty obvious when it gets to the low point, if they are glazed im sure people say sand them, but im not 100% sure about that, hopefully some one will clarify :thumright:
yorkie_chris
09-04-10, 06:20 PM
To Wales? I used to do that once or twice a month with the usual caveat of "be right, sort it when I get back".
3mm on pad is fine. and regarding the tyres, How much grip do you need? You know the roads you're going to be on that well? Not many open enough to go balls out enough that a normal tyre won't cope.
Regarding your braking problem you need to check for warped discs.
To Wales? I used to do that once or twice a month with the usual caveat of "be right, sort it when I get back".
3mm on pad is fine. and regarding the tyres, How much grip do you need? You know the roads you're going to be on that well? Not many open enough to go balls out enough that a normal tyre won't cope.
Regarding your braking problem you need to check for warped discs.
I think I am a drama queen over the tyre to be honest.
The brakes are the annoying one, just been told they have plenty left.
They checked the discs were not warped at the last service and couldn't see a problem, then I asked the MOT guy to check in october and he said they were fine.
Warped disc would judder all the time at any speed would they not? My judder is at about 10mph or less, only occasionally and after very hard braking rather than all the time.
Google brings up loads of people with similar problems but not solutions.
yorkie_chris
09-04-10, 06:35 PM
It's possible the discs have some flaw where expansion under use causes a temporary buckling effect.
What are they like on track? Does the wobble appear and remain?
On the track I generally don't notice it because the speed doesn't really drop low enough. For example brake hard into a tight corner but only down to 30/40mph, then your off again.
But then you can brake hard at the end of a session coming off into the paddock and it will judder pulling up to a stop.
Seriously weird, it's hard to explain. You could have a go and probably be able to replicate it yourself fairly easily.
On the road its relatively easy to make it not do it, on the MESS ride last week it maybe did it once or twice in the 380miles that day.
Just been Reading about the floating discs not floating could cause this too...
I may try take them all apart tomorrow morning before doing anything and give everything a major clean, and rough up the pads.
yorkie_chris
09-04-10, 08:19 PM
Yeah, they expand when hot, inwards and outwards.
If they don't have clearance they buckle.
Is there a recommended way to clean the bobbins on the floating discs. I am thinking copious amount of water and spinning them somehow.
Damn I hate it when there so many little things it could be. But with what you say above this could make sense as to why it does it only occasionally.
yorkie_chris
09-04-10, 08:40 PM
One thing that doesn't make obvious sense is why a buckled disc could work fine at high speed.
Brake cleaner and spin them. Water is ok, brake cleaner better. Try get all the brake dust and shoite out.
Also when's the last time you had your calipers cleaned and greased? Can cause all sorts of strangeness.
Also check front wheel bearings, I could have sworn I'd warped a disc but it turned out to be a rough bearing, only did it under braking.
The brake setup has probably not been greased or cleaned for a while to be honest.
I don't think the brakes are buckled, the judder would be constant at any speed if that was the case surely? And the bearings. were not mentioned at the mot or service and the problem has been present since before then. Thanks for the input by the way.
I think tomorrow is going to be a crash course in stripping brakes down.
Is there anywhere brake wise I should not get brake cleaner? Rubber seals/pistons etc?
How important is it to torque the calipers back on rather than just 'feel'?
Is there anything I really should avoid doing which could knacker something?
How hard can it be... Eek, not like they are important or anything lol
yorkie_chris
09-04-10, 09:32 PM
I don't trust brake cleaner on the seals but it's ok on the pistons.
There's quite a few things where you could knacker something, be careful.
Is there any drag in the front brakes at all or do they release fine?
I haven't stripped any radial brakes so that's as much as I can tell you really.
There is no drag on the front brakes if drag is what I'm thinking it is, a noticable slowing of the wheel when freely spinning?
Can you get brake cleaner on the disc surface and pads?
I'm thinking calipers off first.
Good clean all around.
Pads out, cleaned and regressed on the back.
Maybe wet dry the pad surface incase glazed.
Wet dry disc surface?
Brake cleaner the bobbins on the floating disc as much as possible.
Put back together and test/ hope for the best with fingers crossed lol
yorkie_chris
09-04-10, 09:44 PM
Can you get brake cleaner on the disc surface and pads?
That's what it's for :mrgreen:
Your idea of drag is correct
punyXpress
09-04-10, 09:55 PM
While you've got the spanners out, G, how's your head bearings?
You're really suffering PBSD - post backfire stress disorder. Sorry about that. ;)
Halfords in the morning for brake cleaner and copper grease it is then :p and a dose of bravery ha
yorkie_chris
09-04-10, 09:57 PM
Try a motor factors, it will be cheaper.
muffles
10-04-10, 07:39 AM
I get a slight juddering occasionally on the CBR when pulling up as you describe (i.e. not full on the brakes). Only does it if it's light-medium braking. Feels like the disc is catching then slipping then catching, etc. I might investigate a bit more now the bike is in pieces, seems like the ideal opportunity!
Ok, I fecked up, how do you add brake fluid and bleed brakes :(
piston fell out gettig fluid everywhere, brake are now back together and on the bike. Due to lack of fluid the brake lever does nothing?
Not be making Wales at all at this rate!
I haven't stripped any radial brakes so that's as much as I can tell you really.Absolutely the same as non radial
Ok, I fecked up, how do you add brake fluid and bleed brakes :(
piston fell out gettig fluid everywhere, brake are now back together and on the bike. Due to lack of fluid the brake lever does nothing?
Not be making Wales at all at this rate!
Top up the fluid in the reservoir.*
Attach a hose to one bleednipple (Scottoiler hose or similar might work)stick the other end of the hose into a hole made in the lid of an empty drinks bottle. (attached to the drinks bottle :))
Slowly squeeze the brake lever & hold, loosen the bleed nipple & tighten again.
Slowly release the brake lever & repeat.
Until brake fluid is being pumped by the brake lever through your hose.
Look at the fluid in the hose.
Stop doing it when there are no more air bubbles in the fluid in the hose.
Repeat for the other caliper.
Good Luck & Patience :)
*Make sure it never runs dry or you'll be starting again
Phew managed to get it all back together and bled.
Still does the weird vibration judder thing though.
God knows what it is, perhaps head bearing, wheel bearig or suspension set up.
The mind boggles :( and for now I'll be careful when braking really hard.
I braked really hard from 80 to 0 with no vibration at all then once the suspension has settled a second or so later when you start rolling at 5 to 10mph it does the vibration.
Could this be fork oil not getting back to where it should be sharpish? Which setting would that be that I need to play with, I have 3 types of adjustment.
I'm going to try reducing the front spring preload and increasing compresion damping in the morning after reading the below link which seems quite useful.
It mentions front fork judder, and my forks probably do dive to fast, the cable ties are maybe 1.5" - 1" from the bottom of the forks.
http://www.vtwo.demon.co.uk/firestorm/suspension.htm
yorkie_chris
10-04-10, 06:38 PM
peter verdone website is very applicable to bike you have :)
How old is oil? Fork chatter is more likely to be under harder braking than that
peter verdone website is very applicable to bike you have :)
How old is oil? Fork chatter is more likely to be under harder braking than that
I bought the bike in June 2008 new, but technically its a December 2006 that didnt move for a year and a half before I bought it.
So the fork oil is just over 3 years old.
Just looked at his site, that is a crazy amoumt of detail he goes into.
yorkie_chris
10-04-10, 06:59 PM
Miles?
yorkie_chris
10-04-10, 07:17 PM
Yours same year as PVDs bike? 21mm of chrome showing is bottomed. So if your cable tie is 1" from bottom you are well into bottoming cone area at that
Yours same year as PVDs bike? 21mm of chrome showing is bottomed. So if your cable tie is 1" from bottom you are well into bottoming cone area at that
It's done 7400.
I'll measure the chrome in a mo.
What does bottoming into the cone area mean? Could doing that cause the issue I'm getting?
yorkie_chris
10-04-10, 08:14 PM
You read that section on forks on pvd site? Bottoming cone is last 20mm of travel where you have hydraulic lock and basically no control over what's going on.
No I don't think that is your issue though.
The cable tie is at the 20mm mark, bang on infact. :s
yorkie_chris
10-04-10, 08:28 PM
So you bottomed it at some point...
Cable tie is pointless unless you use it to look at specific condition... EG i know one road with a divot in it... and with 135mm air gap and sag@20mm static it will bottom on that divot if you brake hard from about ton. I don't have oil lock piece working so you can feel metal-metal clack when it happens.
Move cable tie back up and go do a stop on a smooth road, see what travel you are using in that condition.
I'm fairly confused by it all.
My understanding is from reading the PVD page is that I am bottoming out my forks and using that last 20mm... which I really shouldnt be.
Thinking about it I did reset those cable ties today to a certain extent before re-testing my brakes after sticking them all back together.
So that 20mm left is the result of some fairly high speed braking to a stop, in a straight line on smooth tarmac, may have been down hill slightly.
I cant remember where I got the suspension setup from, may stick it all back to default settings, although I am sure I have done that before and it still juddered.
yorkie_chris
10-04-10, 08:41 PM
If you are using up whole travel braking on smooth tarmac you need stiffer springs or more oil.
It could well be that you are getting chatter because you have no travel left... But I would expect that to happen at point of hardest braking not as you are easing off the brakes.
I think the pre load is set relatively soft at the moment... would increasing pre load not improve it?
Thanks again by the way, I am a retard trying to understand this.
yorkie_chris
10-04-10, 08:50 PM
DW I asked way more dumb sh*t than this in my time... I still do :-D
Increasing preload will raise your ride height in any condition. What is your static sag at?
DW I asked way more dumb sh*t than this in my time... I still do :-D
Increasing preload will raise your ride height in any condition. What is your static sag at?
Is that the chrome showing with me on the bike or off the bike :S
Edit google says without rider... just measured it at 115mm of chrome showing.
Edit 2... 115mm is the bike just sat flat on the floor with no rider... I just read somewhere static sag is lifting the front off the ground. I'm not going to be able to do that :(
There is so many different topics with people suffering the same when you google the problem... none of the started topics ever find a solution though lol
http://www.visordown.com/forum/forummessages.asp?utn=191716&dt=4&srchdte=0&v=2&sp=332422698253344120478
This is another one mentioning the bobbins on the floating discs... I cleaned them up tonight quite well some were really tight so will try it again tomorrow if I get a chance to see if its made a difference. This would make quite a lot of sense as the brake will be at their hottest after hard braking.
Will also up the compression damping so its cable tie finishes slighly higher up.
yorkie_chris
10-04-10, 09:36 PM
Bear in mind with comp that you have 2 springs and a force*... comp is damping and cannot support the bike, it can only slow the movement.
With heat my theory is the disc is taking a temporary warp because of lack of clearance.
Bear in mind with comp that you have 2 springs and a force*... comp is damping and cannot support the bike, it can only slow the movement.
With heat my theory is the disc is taking a temporary warp because of lack of clearance.
lack of clearance due to the bobbin things getting clogged with dust/dirt? Because they are dirty the disc is getting hot during hard braking, expanding but having nowhere to move so temporarily warping?
Only getting truely hot when braking hard to a stop due to lack of air movement around the disc at sub 10mph
The cleaning has not worked.
I have just increased my preload twice and the virbrations seem much less, at one point I locked the front end up for a few metres (yes **** myself) interestingly the cable ties still finish about 21mm mark.
Right I just wound the preload back to completely soft.
Default is 5 turns clockwise.
I was running at 7 turns clockwise and getting vibration.
Then I increased in stages until 10 turns clockwise and vibration were much less, struggled to replicate it with locking front up.
The preload has another 5 1/2 turns available. 15 1/2 turns in total.
The cable tie is still finishing at about the 21mm mark, should I just keep increasing pre load until that increases? Does increased preload mean the front locks up easier under hard braking?
I've just changed my rear pads this afternoon and thought I'd post a couple of pic's
New pad showing 5 mm of thickness
http://img442.imageshack.us/img442/6541/006ti.jpg
Old pad with 1.6 mm left on it.
http://img72.imageshack.us/img72/9655/010ljk.jpg
punyXpress
11-04-10, 11:53 AM
Just a thought ( dangerous I know ) but are the grooves REALLY depth gauges or just to clear dust?
defo not depth gauges...
I thought they might help in cooling of the friction pad. but dust clearing sounds better.
Six pages to get to the answer of that one. :lol: I went and had a look on t'net after I posted that to see what everyone else thought. It would appear the groove is there to split the brake surface in half to allow brake dust and stuff to clear the surface better. Although quite a lot of people also use it as a basic guide as to how low the pads are and use it as a basic guide for replacement. So I was wrong (sort of). :)
vBulletin® , Copyright ©2000-2025, Jelsoft Enterprises Ltd.